Search Results (1,619)

Building facades and construction materials are continuously exposed to airborne particulate matter, organic pollutants, and microbial colonization, which cause progressive soiling, aesthetic degradation, and structural deterioration while imposing high maintenance and energy burdens. Photocatalytic titanium dioxide (TiO₂) has emerged as the most widely studied material for imparting self-cleaning functionality to building surfaces, owing to its ability to mineralize adsorbed contaminants under solar irradiation and to modulate surface wettability. This narrative review provides a structured account of TiO₂-based self-cleaning coatings for building materials, organized around three complementary themes: surface mechanisms, performance metrics, and outdoor durability. We first rationalize the two intertwined self-cleaning mechanisms—photocatalytic oxidative degradation and photoinduced superhydrophilicity—and their combination with physically repellent (superhydrophobic/superamphiphobic) wetting states. We then survey the principal coating-design strategies, including morphology and facet engineering, SiO₂-TiO₂ composites, metal/non-metal doping and heterojunction construction for visible-light activation, and dual-functional photocatalytic–superhydrophobic systems, and their integration into cementitious substrates, natural stone and cultural heritage, and transparent glass/photovoltaic surfaces. The quantitative metrics used to benchmark self-cleaning performance—water contact angle, dye photodegradation, NO_x and VOC abatement, and antimicrobial activity—are critically discussed together with the limitations of standardized laboratory tests. Finally, we analyze the weathering-induced deactivation pathways (photocatalyst leaching, surface contamination by soluble salts, and UV aging of organic matrices) and the emerging strategies for durable coatings, including inorganic binders, light-driven hydration, and defect- and heterojunction-engineered photocatalysts. The review concludes with an outlook on the open challenges that must be addressed to translate these coatings from laboratory demonstrations to long-lived, large-scale building applications. Full article

Nanomaterials have emerged as key platforms for environmental remediation owing to their tunable surface chemistry, high specific surface area, and multifunctional physicochemical properties. This review provides a critical comparison between conventional nanomaterials (CNMs) and phyto-mediated nanomaterials (PMNs), with particular emphasis on material design, surface chemistry, pollutant removal mechanisms, environmental performance, and sustainability. CNMs, including metal and metal oxide nanoparticles, carbon-based nanomaterials, and hybrid nanocomposites, offer excellent adsorption, photocatalytic, redox, and antimicrobial performance but remain constrained by concerns regarding toxicity, environmental persistence, and energy-intensive synthesis. PMNs provide a greener alternative by integrating plant-derived surface chemistry with nanomaterial functionality, potentially reducing reliance on hazardous synthesis reagents while modifying interfacial interactions relevant to environmental remediation. The review critically discusses the mechanistic roles of adsorption, surface complexation, photocatalytic degradation, electron-transfer processes, and reactive oxygen species (ROS) generation in pollutant removal. Recent advances in water purification, soil and groundwater remediation, carbon sequestration, and climate-related environmental applications are comprehensively summarized. Finally, current challenges associated with reproducibility, scalability, environmental safety, life-cycle assessment, and regulatory considerations are critically analyzed, together with future perspectives toward the rational design of sustainable nanomaterials for next-generation environmental remediation technologies. Full article

Dental resin composites are widely used for direct restorations, yet their longevity remains limited by biofilm accumulation and secondary caries at the tooth–restoration interface. Unlike previous reviews that have primarily organized antibacterial dental materials according to antimicrobial agents or mechanisms, this narrative review evaluates antibacterial resin composites from a polymer-composite design perspective, integrating molecular architecture, network immobilization, filler–matrix interactions, polymerization, and aging. Leachable agents such as chlorhexidine provide early antibacterial effects but are constrained by reservoir depletion, water sorption, and release-related material changes. In contrast, covalently immobilized quaternary ammonium monomers provide sustained surface-associated activity without continuous release, although their performance depends on molecular structure, concentration, degree of conversion, and network properties. Antibacterial nanoparticles and bioactive glass fillers provide composition-dependent ion-mediated, photocatalytic, pH-modulating, and remineralizing effects, while their performance depends strongly on particle characteristics, dispersion, and formulation. Multifunctional systems further combine antibacterial activity with protein repellence, mineral protection, and rechargeable ion release. Overall, the evidence indicates that durable antibacterial performance cannot be considered independently of polymerization, mechanical integrity, aging stability, and biocompatibility. Future development should therefore prioritize clinically relevant multispecies biofilm models, standardized aging protocols, structure–property analysis, and long-term in vivo and clinical validation. Full article

Extending the stochastic STIRPAT framework, this study investigates the impacts of institutional quality, technological progress, and natural resource dependency on CO₂ emissions across the Gulf Cooperation Council (GCC) from 1995 to 2021. Econometrically, the framework integrates a multi-estimator matrix comprising FMOLS, PCSE, and Panel GMM techniques to control for endogeneity, parameter heterogeneity, and cross-sectional dependence. The empirical parameters reveal that institutional quality and renewable energy consumption exert a highly robust, universally consistent carbon-mitigating effect across all models (FMOLS: −0.2997; PCSE: −0.3044). Conversely, economic growth, non-renewable energy utilization, and urbanization act as the primary structural drivers of degradation. Crucially, the effects of technological innovation and resource dependence are model-dependent; they show statistical significance strictly within long-run FMOLS parameters (−0.0287 and +0.1339, respectively) but turn insignificant under cross-sectional corrections (PCSE/GMM), highlighting that resource wealth is highly conditional. Furthermore, the analysis uncovers a unique demographic paradox in the GCC, where transient foreign labor inflows cause aggregate population growth to exhibit a stable carbon-mitigating response (−0.0207). Policy implications demonstrate that unilateral interventions are insufficient due to cross-sectional dependencies. Instead, mitigating emissions demands an inter-country correlated framework through mechanisms like the Gulf Cooperation Council Interconnection Authority (GCCIA). Finally, the study bridges the macroeconomic–engineering nexus, arguing that regional innovation must transition toward active carbon utilization clusters, specifically electro-, thermo-, and photocatalytic CO₂ conversion systems using porous crystalline metal–organic frameworks (MOFs) to support the 2030 Sustainable Development Goals (SDGs 7, 12, and 13). Full article

In this work, flower-like Bi₂MoO₆ microspheres were first prepared by solvothermal synthesis. Ag₂CrO₄ nanoparticles were then deposited in situ onto the Bi₂MoO₆ surface, leading to the formation of a Bi₂MoO₆/Ag₂CrO₄ n–n heterojunction nanocomposite photocatalyst. Through characterization technologies and visible-light degradation experiments, the photocatalytic behavior and degradation mechanisms of nanocomposites were explored. The results demonstrated that Ag₂CrO₄ block-like particles were uniformly anchored onto the surface of the flower-like Bi₂MoO₆ microspheres. The diffraction peaks, lattice fringes, XPS binding energies and FT-IR absorption bands of the composite samples were in good agreement with those of the individual components. Construction of the heterojunction remarkably broadened the optical response of Bi₂MoO₆, extending the absorption edge from 497 to 713 nm. The band gap decreased to 1.52 eV, lower than the values measured for either constituent semiconductor. Moreover, the nanocomposite showed a markedly lower photoluminescence emission intensity. The Bi₂MoO₆/Ag₂CrO₄ photocatalyst removed maximum 99.43% of Rhodamine B (RhB) within 60 min under visible-light illumination. The photocatalytic activity of nanocomposite with a Bi₂MoO₆:Ag₂CrO₄ molar ratio of 1:1 was 3.56 times that of pure Bi₂MoO₆, while the kinetic constant reached 0.0570 min⁻¹, exceeding those of Bi₂MoO₆ and Ag₂CrO₄ by factors of 13.90 and 2.26, respectively. After five consecutive reuse cycles, the photocatalyst still removed more than 85% of RhB from aqueous solution. Optimal degradation performance was obtained using 0.50 g/L of photocatalyst and the initial RhB concentration of 10 mg/L. The photocatalytically generated active species h⁺ and ·O₂⁻ can effectively decompose the chromophores of RhB molecules in water. Finally, the degradation mechanism of RhB by nanocomposites was proposed. Full article

The continuous release of pharmaceutical contaminants such as naproxen (NPX) into aquatic environments poses substantial ecological risks. In this study, a series of visible-light-responsive bismuth oxychloride-iodide (BiOCl_xI_1−x) solid solutions were synthesized via a simple one-step solvothermal method. XRD analysis confirmed the formation of a tetragonal matlockite-type solid solution, while SEM and TEM observations revealed three-dimensional flower-like hierarchical microspheres assembled from ultrathin nanosheets. Among the prepared samples, BiOCl_0.3I_0.7 exhibited the highest visible-light photocatalytic activity toward NPX degradation, achieving a removal efficiency of 87% within 60 min. Its apparent pseudo-first-order rate constant was 0.0740 min⁻¹, the highest among the investigated compositions. Experimental measurements showed composition-dependent band-gap narrowing, while representative DFT calculations indicated that I-for-Cl substitution modifies the valence-band electronic states, providing a qualitative electronic-structure explanation for the enhanced visible-light response. Evaluation of operational parameters showed that NPX degradation was favored at lower initial NPX concentrations and under acidic conditions, whereas humic acid and bicarbonate (HCO₃⁻) inhibited the process. TOC analysis further confirmed partial mineralization of NPX during photocatalysis. Electron paramagnetic resonance (EPR) analysis and reactive-species trapping experiments indicated that photogenerated holes (h⁺), singlet oxygen (¹O₂), and superoxide radicals (O₂^•−) were the dominant reactive species involved in NPX degradation. These findings demonstrate the potential of band-gap-engineered bismuth-based solid solutions for environmental remediation. Full article

Developing portable and reliable systems for online monitoring of antibiotic degradation in water is essential for studying, optimizing, and improving their efficiency. In this work, we introduce an impedimetric sensor-based system for online monitoring of the photocatalytic degradation of levofloxacin (LVX). The sensor consists of graphite pencil leads (GPL) modified with molecularly imprinted polymers (MIP) to ensure specificity and enhance sensitivity. The sensor was evaluated in a concentration range of 0 to 40 mg/L of LVX, achieving a detection limit of 1.3 mg/L, and subsequently tested in a photocatalytic degradation process. All measurements were validated using high-performance liquid chromatography (HPLC). Based on the results, the proposed system is a promising alternative to conventional analytical methods for online monitoring of degradation processes. This approach facilitates the optimization of degradation mechanisms, minimizing resource consumption and reducing analysis and operation times, especially in resource-limited environments. Full article

Confronted with severe global challenges, including water scarcity, excessive use of chemical fertilizers and pesticides, and heavy metal contamination in soils, conventional agricultural technologies exhibit marked limitations in integrated water–fertilizer management and non-point source pollution control. Leveraging their excellent water retention capacity, intelligent sustained-release properties, and environmental responsiveness, hydrogels offer innovative solutions to advance sustainable agricultural development. This review comprehensively outlines the fundamental types, crosslinking mechanisms, and key functional properties of hydrogels, with a focused discussion on their agricultural deployment as high-efficiency soil conditioners, fertilizer vectors, and pesticide carriers; it deciphers the microscopic water-holding mechanisms under the tristate water model, delineates the divergent water-uptake and retention behaviors between ionic and non-ionic hydrogels, and clarifies the cyclic water-holding and release mechanisms of hydrogels during soil amelioration. Thise paper further synthesizes hydrogel-enabled environmental remediation applications, in which heavy metals and pesticide residues in soils and aquatic systems are removed via functional-group coordination adsorption or photocatalytic degradation; concurrently, hydrogels have been shown to activate plant systemic immunity through calcium-signaling pathways, thereby inducing broad-spectrum antiviral defense responses. Moreover, hydrogels can be integrated into precision agriculture frameworks to enable real-time monitoring of crop physiological status and to support targeted irrigation and fertilization management. This work also evaluates the role of hydrogels in promoting seed germination, root system development, crop metabolic regulation, and stress resilience, while introducing tailored application strategies across distinct plant growth stages. Their documented economic advantages include water conservation, enhanced crop yields, reduced dependence on synthetic fertilizers, and lower labor costs. Nevertheless, the large-scale implementation of hydrogels continues to face multifaceted challenges—particularly poor degradability and latent ecological risks, as conventional polyacrylamide (PAM)-based gels resist soil mineralization and retain potentially neurotoxic monomers, leaving a critical gap in multi-annual field data concerning their non-target interference with native soil aggregate evolution, pore distribution, and rhizospheric carbon–nitrogen footprints. Mechanistically, many hydrogels with tensile strengths below 1 MPa are highly susceptible to three-dimensional network collapse under high-salinity osmotic shock and tillage mechanical stress, exhibiting a precipitous drop in water retention after more than three wet–dry cycles due to deficient long-term structural stability. Compounding these technical gaps are elevated production costs and low farmer adoption, driven by the absence of texture-specific performance thresholds—such as an available water increment ≥ 40% for sandy soils—and the lack of established life-cycle cost models and farmer incentive mechanisms for bio-based hydrogels. Moving forward, hydrogel technology should pivot toward materials innovation and cost-reduction engineering to broaden its applicability, employ ≥3-year, multi-habitat regional trials to delineate ecological benefit–risk boundaries, and ultimately position hydrogels as pivotal enablers of sustainable, green agricultural paradigms. Full article

The performance of coatings, corrosion barriers, photocatalysts, and tribological materials is greatly influenced by in situ surface properties, requiring highly sensitive and reproducible operando surface characterization methods. We previously developed a temperature-programmed photoelectron emission (TPPE) method to clarify electron transfer behavior on light-irradiated metal surfaces. TPPE is sensitive to surface temperature and prior chemical exposure, which affect the total photoemitted electron count (N_T), the photothreshold, and the activation energy derived from Arrhenius plots of N_T obtained during heating–cooling cycles. This study examines the reproducibility of TPPE data and the TPPE mechanisms for Cu₂O/Cu surfaces subjected to mechanical abrasion, cleaning, plasma treatment, and subsequent immersion in organic liquids. The resulting Arrhenius plots reveal both positive and negative activation energies, depending on the treatment conditions. Negative activation energies during cooling are associated with photoredox-mediated emission. TPPE is attributed to oxygen vacancies within the Cu₂O surface layer, which is interfaced with metallic Cu, serving as a direct probe of these vacancy-related states. The TPPE characteristics (N_T intensity and activation energy) following exposure to various polar and nonpolar organic molecules (e.g., acetone, toluene, hexane, and ethanol) correlate with the electronic properties of these vacancies, consistent with previous observations for ambient air, alcohol, and water vapor exposure. Under illumination, Cu₂O vacancy states enhance photocarrier extraction (electrons and holes) and accelerate surface redox reactions within adsorbed thin films, thereby improving photocatalytic performance. Notably, the solvent’s reciprocal dielectric constant significantly influences TPPE, indicative of electrostatic surface–solvent interactions. Finally, the TPPE mechanism is discussed in the context of antiviral inactivation at the metallic copper–environment interface. Full article

Cyanobacteria are promising platforms for bioenergy, carbon sequestration, and bioproduct synthesis, but their photosynthetic efficiency is limited by suboptimal light utilization, electron transport constraints, and environmental stress. Titanium dioxide nanoparticles (n-TiO₂) have emerged as powerful photocatalytic materials that can enhance light absorption, modulate electron transport, and influence the redox balance in biological systems. This review advances the concept of photocatalytic-biological coupling, in which n-TiO₂ functions as artificial light amplifiers that augment cyanobacterial photosynthesis. Current evidence on the physicochemical properties of n-TiO₂, their interactions with cyanobacterial cells, and their effects on photosystems, electron transport chains, and downstream metabolic processes is examined. Particular emphasis is placed on the integration of photophysical and biological mechanisms, including reactive oxygen species (ROS)-mediated signaling, proton motive force (PMF) enhancement, and adenosine triphosphate (ATP) synthesis. Emerging approaches, including nano–bio interface engineering, environmental biotechnology applications, and artificial intelligence-guided optimization, are highlighted. By bridging photophysics, cellular bioenergetics, and computational design within a unified mechanistic framework, this review establishes the scientific foundation needed to translate photocatalytic–biological coupling into scalable and biotechnologically deployable nano-enabled photosynthetic systems. Full article

Fe^II-doped zinc ferrite nanocrystals (Fe^II_xZn_1-xFe^III₂O₄) were prepared via a sol–gel approach in the presence of polyvinyl alcohol as a stabilizer and assessed for their capability to eliminate crystal violet (CV) dye from water-based solutions. The structural and surface characteristics of the prepared materials were examined by XRD, HRTEM, FESEM, ATR–FTIR, XPS, UV–visible spectrophotometer and BET analyses. XRD patterns confirmed the formation of a cubic spinel ferrite structure (Fd-3m), indicating successful incorporation of Fe^II into the ZnFe₂O₄ lattice. ATR–FTIR spectra showed characteristic metal–oxygen vibrations at the tetrahedral and octahedral sites. XPS analysis confirmed the coexistence of Fe^II and Fe^III species, which may promote interfacial charge transfer and redox reactions. HRTEM and FESEM images showed particle agglomeration and grain growth after calcination at 700 °C. Fe^II_0.2Zn_0.8Fe^III₂O₄ exhibited the highest photocatalytic performance, achieving 97.2% degradation of CV under optimized conditions. The effects of contact time, catalyst dosage, initial dye concentration, and pH were systematically studied. The maximum removal efficiency was obtained at pH 10 using 0.075 g catalyst for 20 mg L⁻¹ CV solution within 40 min. Freundlich isotherm models exhibited the strongest correlation (R² = 0.918), pointing to multilayer adsorption occurring across a non-uniform nanoparticle surface. The Dubinin–Radushkevich analysis returned an adsorption energy of 3.01 kJ mol⁻¹, implying that physical forces predominantly control the adsorption mechanism. Kinetic investigations revealed a two-stage CV uptake pathway: fast initial binding at exterior surface sites, succeeded by a slower migration of dye molecules into the internal pores of the adsorbent. Full article

In this paper, we have investigated the photocatalytic performances of some yttrium-doped ZrO₂ films for decomposing Rhodamine B and Methylene Blue. The as-deposited thin films (obtained by RF magnetron sputtering) were heat-treated to stabilize their structure. To assess the films’ characteristics, a group of analytical methods (XRD, XPS, AFM and DRS) allowed for the determination of their structural, surface, and optical properties. These characteristics were correlated with the observed photocatalytic activity and wetting behaviour. The Y-doped ZrO₂ film with medium nanoparticle size and a high contribution of the oxygen vacancy is found to be more efficient in Rhodamine B and Methylene Blue photodegradation; the 100% degradation efficiency was reached in 70 min and 40 min, respectively, for the 3 mg/L solution dye. The photodegradation mechanism is driven by photogenerated holes, and a possible reaction mechanism was proposed. By investigating the charge carrier separation at the film–ITO interfaces, made through a comparative analysis of their determined band edge potentials, we conclude that the transfer is not possible in either of the semiconductor pairs, so ITO does not “help” the photocatalytic process. Full article

Solar-driven photocatalytic water splitting is a promising approach for green hydrogen production. Despite the great potential of g-C₃N₄ photocatalysts, non-metal doping studies currently suffer from conflicting results and unclear doping configurations. Herein, first-principles calculations were adopted to compare P-, O-, and S-doped g-C₃N₄. P-g-C₃N₄ with P substituting N shows the best stability, a narrower band gap, and enhanced visible light absorption. It achieves high carrier mobility and suitable band edges for overall water splitting, with a maximum STH efficiency of 15.8%. This work clarifies doping mechanisms and offers solid theoretical support for developing high-performance g-C₃N₄-based photocatalysts. Full article

Biochar is a porous carbonaceous material synthesized through the pyrolysis of diverse biomass resources, including agricultural and forestry residues as well as livestock manure. It possesses superior characteristics such as a large specific surface area, adjustable pore architecture, abundant surface functional groups, and favorable electrical conductivity. With the increasingly severe global energy shortage and environmental pollution problems in recent years, biochar has emerged as a green, low-cost functional material with distinct application superiority in multiple key research directions, including energy storage and conversion, chemical catalysis, environmental restoration, and signal sensing and detection. This study comprehensively summarizes the latest research advances of biochar in the aforementioned application fields, focusing on innovative achievements in photocatalytic and electrocatalytic hydrogen generation, supercapacitors and electrochemical energy storage systems, persulfate activation technology, carbon dioxide capture, remediation of heavy metal and organic contaminants, volatile organic compound (VOC) adsorption, as well as electrochemical sensing devices. Existing research results demonstrate that modification strategies including metal and non-metal doping, surface oxidation treatment, and compounding with semiconductors or metal oxide materials can effectively improve the catalytic activity and functional performance of biochar. Furthermore, this paper prospects the future interdisciplinary development trends of biochar, analyzes the existing research gaps in mechanism exploration, structural optimization design, and industrial large-scale preparation, and provides theoretical and practical references for the further popularization and application of biochar in sustainable energy development and environmental governance fields. Full article

Using bismuth oxide (Bi₂O₃) as the matrix and employing a doping modification strategy to introduce the rare-earth element La, this study prepared La/Bi₂O₃ visible-light-responsive photocatalysts with different doping ratios. The research systematically investigated the regulation mechanisms of La doping on the material’s phase structure, microstructure, band structure characteristics, and visible-light photocatalytic performance. The results indicate that an appropriate amount of La³⁺ equivalently substitutes Bi³⁺ in the lattice, inducing the complete transformation of pure α-Bi₂O₃ into the tetragonal β-Bi₂O₃ phase while maintaining the integrity of the crystal framework. Meanwhile, the modulation of the local electronic structure caused by La³⁺ substitution effectively narrows the bandgap width and broadens the visible-light response range; it also acts as an electron trap to significantly suppress the recombination of photo-generated electron–hole pairs, thereby enhancing charge transport efficiency. Visible-light catalytic degradation experiments confirmed that 4% La/Bi₂O₃ exhibits the optimal degradation kinetics for RhB, achieving a 72.88% degradation rate of Rhodamine B within 60 min of visible-light irradiation. The first-order reaction rate constant was 23 times that of pure Bi₂O₃, and the material demonstrated good stability under repeated cycles. Radical trapping experiments indicated that the order of contribution of active species was ·O₂⁻ > h⁺ > ·OH, with the superoxide radical (·O₂⁻) being the dominant active species. This study confirms that appropriate lattice doping with La can synergistically optimize the structure and optoelectronic properties of Bi₂O₃, providing experimental evidence and theoretical references for the rational design of highly efficient and stable visible-light-responsive Bi₂O₃-based photocatalytic materials. Full article